title: Design and analysis of mismatch probes for long oligonucleotide microarrays.
abstract: BACKGROUND
  Nonspecific hybridization is currently a major concern with microarray technology. One of most effective approaches to estimating nonspecific hybridizations in oligonucleotide microarrays is the utilization of mismatch probes; however, this approach has not been used for longer oligonucleotide probes.
  
  
  RESULTS
  Here, an oligonucleotide microarray was constructed to evaluate and optimize parameters for 50-mer mismatch probe design. A perfect match (PM) and 28 mismatch (MM) probes were designed for each of ten target genes selected from three microorganisms. The microarrays were hybridized with synthesized complementary oligonucleotide targets at different temperatures (e.g., 42, 45 and 50 degrees C). In general, the probes with evenly distributed mismatches were more distinguishable than those with randomly distributed mismatches. MM probes with 3, 4 and 5 mismatched nucleotides were differentiated for 50-mer oligonucleotide probes hybridized at 50, 45 and 42 degrees C, respectively. Based on the experimental data generated from this study, a modified positional dependent nearest neighbor (MPDNN) model was constructed to adjust the thermodynamic parameters of matched and mismatched dimer nucleotides in the microarray environment. The MM probes with four flexible positional mismatches were designed using the newly established MPDNN model and the experimental results demonstrated that the redesigned MM probes could yield more consistent hybridizations.
  
  
  CONCLUSIONS
  This study provides guidance on the design of MM probes for long oligonucleotides (e.g., 50 mers). The novel MPDNN model has improved the consistency for long MM probes, and this modeling method can potentially be used for the prediction of oligonucleotide microarray hybridizations.
authors.affiliation: Institute for Environmental Genomics, Department of Botany and Microbiology, the University of Oklahoma, Norman, OK 73019, USA. dengye@ou.edu
authors.forename: Ye
authors.initials: Y
authors.lastname: Deng
authors.forename: Zhili
authors.initials: Z
authors.lastname: He
authors.forename: Joy D
authors.initials: JD
authors.lastname: Van Nostrand
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D020137:Base Pair Mismatch; D008962:Models, Theoretical; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D015345:Oligonucleotide Probes / Q000737:chemistry*; D013696:Temperature
chemical_list: D015345:Oligonucleotide Probes